48 



It may be obtained from the last of August, -when it is most frequently 

 met with in a young state, until the last of June, at which time the 

 young ones of the autumn season have developed to full-grown ani- 

 mals. In an adult state it measures nearly an inch across the disc, 

 exclusive of the tentacles, and about the same in height. It varies in 

 color from green, which is the most common tint, to deep olive ; from 

 light yellow to reddish brown, or from light violet to the deepest pur- 

 ple. In form it is octagonal, and most frequently it so comports itself 

 that the four sides opposite the bifarious genitalia are shorter than 

 those alternating with them, but frequently the same individual re- 

 verses the order of things, and the latter become either as short, or 

 even shorter, than the first. From this we infer that the specific dif- 

 ferences, based upon the approximation of the bunches of tentacles, 

 two and two, are entirely erroneous. As these animals are very sen- 

 sitive and irritable, they contract upon the least disturbance ; and, as 

 the muscular system is most highly developed in the region which lies 

 about the four partitions of the disc, it is most natural that when the 

 creature contracts it should draw the two halves of the genitalia and 

 the bunches of tentacles together more closely here than at the alter- 

 nate quarters ; hence arises the frequently-observed quadrate outline 

 of the disc. Again, in regard to another feature oftentimes employed 

 to discriminate between different species or even groups, I would say 

 that the absence of auricles does not indicate a specific difference 

 from those individuals possessing them, but rather an accidental atro- 

 phy of these organs ; and that tlais fact is to be classed in the same 

 category as the occasional development of one of the tentacles into 

 a semiauricular body. I have always noticed that individuals in such 

 a condition have an unnatural appearance ; that they are not so lively 

 as the others, and ajjpear to be diseased. I believe this species to be 

 identical with the L. auricula of the English coast. The most charac- 

 teristic figure that I know of, although unsatisfactory, is in Gosse's 

 little book, " The Aquarium." 



In order to contrast the structure of Lucernaria with that of the 

 Steganopthalmatan Medusa3, and, moreover, in order that I may not 

 complicate matters, I will compare it, organ for organ and part for 

 part, with one of our most common medus£e, Aurelia flavidula, 

 Agassiz. The aboral side, which corresponds to the so-called dorsal 

 region of other Acalephas, projects at the apex into a moderately long 

 columnar body, usually called the peduncle of Lucernaria. With the 

 exception of the four equidistant channels and the four muscular cords 

 which alternate with them, the peduncle is a solid gelatiniform mass, 

 covered by the outer wall. This gelatiniform substance also consti- 

 tutes the bulk of the disc, filling the entire space between the outer 

 wall and the inner or lining wall of the digestive cavity, and is direct- 



